The Limulus Amoebocyte Lysate Assay and the Direct Epifluorescent Filter Technique as Estimators of Potential Shelf-life of Pasteurized Fluid Milk

Abstract

The Limulus Amoebocyte Lysate Assay, Direct Epifluorescent Filter Technique and modified Psychrotrophic Bacteria Count were used to indicate potential shelf-life of pasteurized fluid milk. Commercial whole milk samples, stored at 7°C, were analyzed for bacterial and biochemical parameters, as well as for potential shelf-life by daily sensory evaluation. Each sample was evaluated before and after the following preliminary incubations: milk alone, milk with benzalkonium chloride, milk and broth, and milk and broth with benzalkonium chloride. The Limulus Amoebocyte Lysate Assay, Direct Epifluorescent Filter Technique, and modified Psychrotrophic Bacteria Count in conjunction with the preliminary incubations, produced relatively high correlations to shelf-life (−0.78, −0.85, and −0.86 respectively). Thus, these bacterial detection techniques could be used as rapid methods of shelf-life estimation.